[visualization] Access to a potential null pointer in interactor_style (#5503)

Within the OnKeyDown method of PCLVisualizerInteractorStyle, the pointer
to the currentRenderer is tested for null then it is used to render outside
the scope of the test. The rendering is now done only if the pointer is
not null.

Author: Nandite

visualization/src/interactor_style.cpp

@@ -1050,11 +1050,14 @@ pcl::visualization::PCLVisualizerInteractorStyle::OnKeyDown ()
       {
         FindPokedRenderer(Interactor->GetEventPosition ()[0], Interactor->GetEventPosition ()[1]);
         if(CurrentRenderer)
+        {
           CurrentRenderer->ResetCamera ();
+          CurrentRenderer->Render ();
+        }
         else
+        {
           PCL_WARN ("no current renderer on the interactor style.\n");
-
-        CurrentRenderer->Render ();
+        }
         break;
       }